Impenetrably is a word used to describe something that is impossible to penetrate or get through. This can be someone's attitude, a material or an object. However, there are other synonyms you can use instead of "impenetrably". These include terms like impenetrable, impermeable, unbreakable, indestructible, invincible, impervious and armored. Each of these words describes something that is strong and unyielding in its nature, and cannot be easily overcome or destroyed. By using these synonyms, we can express a similar meaning with a unique perspective. In conclusion, there are numerous synonyms available to make our language more vibrant and expressive, and writers must utilize them for better writing.